The present invention relates generally to pipe joints, and in particular to dual-member pipe joints, systems of dual-member pipe joints comprising dual member drill strings, boring machines using dual-member pipe joints and to methods of boring horizontal boreholes using dual-member pipe joints.
The present invention is directed to a pipe joint. The pipe joint comprises an elongate, hollow outer member having an inner surface and an outer surface and a pin end and a box end which are correspondingly threaded. An elongate inner member is arranged general coaxially within the outer member forming an annular space between the inner member and the inner surface of the outer member. The inner member has a geometrically-shaped pin end and a box end corresponding to the shape of the pin end of the inner member. The pin end of the inner member is slidably receivable in connector-free, torque-transmitting engagement with the box end of a similarly formed inner member.
The present invention further includes a system of pipe joints comprising a plurality of pipe joints as hereinabove described. The pin end of the inner member of each pipe joint is connectable to the box end of the inner member of another one of the plurality of pipe joints. The pin end of the outer member of each pipe joint is connectable to the box end of the outer member of another one of the plurality of pipe joints. When connected, the outer members of the plurality of pipe joints form a passageway extending the length of the system of pipe joints.
The present invention further comprises a horizontal boring machine comprising a frame, a rotary machine supported on the frame, a drill string and a directional boring head. The drill string has a first end, which is operatively connectable to the rotary machine to drive the rotation of the drill string, and a second end, which is attachable to the directional boring head. The drill string is comprised of a system of pipe joints as hereinabove described.
Still further, the present invention includes a horizontal boring machine as hereinabove described wherein the rotary machine further comprises a carriage supported on the frame, an inner member drive group, an outer member drive group and a biasing assembly. The inner member drive group is supported on the carriage assembly and drives the rotation of the inner members comprising the drill string. The inner member drive group comprises an inner member drive motor, an inner spindle and a torque-transmitting member for transmitting torque from the inner member drive motor to the inner spindle. The inner spindle is connectable to the inner member of a pipe joint loaded on the boring machine for connection to the drill string or to the inner member at the first end of the drill string.
The outer member drive group is supported on the carriage assembly and drives the plurality of outer members comprising the drill string. The outer member drive group comprises a motor, an outer spindle and a torque-transmitting member for transmitting torque from the outer member drive motor to the outer spindle. The outer spindle is connectable to the outer member of a pipe joint loaded on the boring machine for connection to the drill string or to the outer member at the first end of the drill string.
The biasing assembly is supported on the carriage and is adapted to urge substantially simultaneous, slideable, connector-free, torque-transmitting engagement of the inner member of a pipe joint loaded on the boring machine for connection with the rotary machine and with the inner member at the first end of the drill string.
Still further, the present invention includes a horizontal boring machine comprising a plurality of pipe joints as hereinabove described.
Finally, the present invention includes a method for making directional boreholes using a boring machine having a rotary machine capable of simultaneously rotating and axially advancing a directional boring head attached to a drill string comprised of a plurality of connectable pipe joints constructed in accordance with the present invention. The method comprises the steps of; first, making one connection per additional pipe joint loaded on the boring machine for connection with the drill string by simultaneously axially advancing the rotary machine and transmitting torque from the rotary machine to the additional pipe joint, whereby the outer member of the new pipe joint substantially simultaneously connects with the rotary machine and with the outer member at the first end of the drill string while the inner member of the additional pipe joint substantially simultaneously connects in slideable, connector-free, torque-transmitting engagement with the rotary machine and with the inner member at the first end of the drill string, and, second, axially advancing and rotating the directional boring head to make a borehole.